WO2016162590A1

WO2016162590A1 - Filter plate

Info

Publication number: WO2016162590A1
Application number: PCT/FI2015/050241
Authority: WO
Inventors: Wuqiang QI; Zheng Lu
Original assignee: Minexcell Oy
Priority date: 2015-04-09
Filing date: 2015-04-09
Publication date: 2016-10-13

Abstract

The invention relates to a filter plate (10) of a filter disc (30), which has a circle sector shape and a planar structure. The filter plate (10) is formed as a sandwich structure comprising a supporting base (26) and a filtration element (16) on both planar sides of the filter plate (10).

Description

Filter plate

In general present invention relates to a filter plate of a vacuum filter. More specifically the present invention relates to a filter plate according to preamble part of claim 1 . It is known from prior art to use filtration processes for dewatering concentrates and tailings in mining industry. In the filtration process a slurry or solid liquid mixture is forced through a filter, with which solids are retained and liquid is passed through. This process is generally applied by different filtration types comprise vacuum filtration, depth filtration, pressure filtration as well as gravity and centrifugal filtration.

Vacuum filters are commonly used in mining industry for dewatering of mineral concentrates. In vacuum filters the driving force for filtration is generated by vacuum and cake formation in vacuum filtration is based on generating suction within the filtrate channels. Several different types of vacuum filters are known from prior art, for example rotary vacuum drum filters and rotary vacuum disc filters. Rotary vacuum disc filters are used for filtering slurry on a large scale, such as the dewatering of mineral concentrates. The vacuum disc filter typically comprises a plurality of filter discs arranged in line co-axially around a cen- tral pipe or shaft and each filter disc typically comprises several filter plates. The filter plates are mounted circumferentially in a radial plane around the central pipe or shaft to form the filter disc.

Certain vacuum disc filters benefit from capillary suction power to form a filtrate cake and to dry it. Those filters demand much smaller vacuum pumps for op- eration, hence bring significant energy saving.

Their filter plates as known from prior art are typically made of ceramic material. They are thus fragile and therefore susceptible to breakage. When impacted by oversized solid particle or impacted by excessive solid accumulated in the slurry basin, a ceramic filter plate may be cracked or broken. Ceramic fragment may cause further damage to other ceramic plates and to other parts of the filter.

Another disadvantage of a ceramic filter plate known from prior art is the fastening pattern of the plate to the central shaft by the bolts located at one side of the plate which is close to the shaft. This fastening pattern sets challenges to the straightness and alignment of the filtration disc that is formed by several plates, especially during the operation.

Moreover, the fastening pattern of the ceramic filter plate at one side known from prior art set restriction on the size and capacity of a filtration plate, especially when high specific weight of ceramic material is taken into consideration.

An object of the present invention is to create a new type of a filter plate, in which the disadvantages and limitations of prior art are eliminated or mitigated.

An object of the present invention is to create a filter plate, which is more du- rable and more resistant to impact with less specific weight compared to ceramic plates known from prior art.

A particular, conditional object of the present invention is to create a filter plate structure in which installation and fastening of the filter plates to form a filter disc is easy, precise and secure. In order to achieve the above mentioned objects and those that will be disclosed later, filter plate according to the invention is mainly characterized by the features of the characterizing part of claim 1 . Advantageous features and aspects are presented in the dependent claims.

According to the invention the filter plate has a circle sector shape and a pla- nar structure, wherein the filter plate is formed as a sandwich structure comprising a supporting base and a filtration element on both planar sides of the filter plate.

According to an advantageous feature of the invention the materials for the supporting base and for the filtration elements are selected and optimized in- dependently to best meet process requirements.

According to an advantageous feature of the invention the supporting base is made of metallic or polymeric or composite material, advantageously of carbon fiber composite material. According to an advantageous feature of the invention the material of the filtration element is filtration cloth material, mesh material, ceramic material, ultrafiltration membrane advantageously ceramic material and ultrafiltration membrane that provide the capillary suction phenomenon. According to an advantageous feature of the invention the filtration elements are attached on both sides of the supporting base by adhesive or by welding.

According to an advantageous feature of the invention a connecting rod goes through the space between two neighboring filter plates. One end of the connecting rod is fastened on the shaft of the filter. The other end of the connect- ing rod is fastened by a locking bar that is fit into the groove at the top of two neighboring plates.

According to an advantageous feature of the invention filter plates are connected to each other by connecting rods to form a circular filter disc and are attached to the shaft of a disc filter by connecting rods. According to an advantageous feature of the invention the supporting base has protrusions that protrude from the supporting base bottom forming liquid removal channels.

According to an advantageous feature of the invention the supporting base has thus several apart from each other located protrusions on each side of the supporting base arranged in curved protrusion rows in a pattern, advantageously in mirror pattern in respect of an imaginary central axis running in radius direction of the sector design of the filter plate.

The filter plate according to the invention is formed as a sandwich structure comprising two different types of main parts, one of which is a supporting base and the other is the filtration element. On each side of the supporting base a filtration element is attached.

The supporting base is made of metallic or composite material; advantageous materials are stainless steel and carbon fiber reinforced composite material, which both have good impact resistance, tear strength and toughness proper- ties.

The filtration element material is selected according to the requirements of the filtration process. It can be filtration cloth material, mesh material, ceramic ma- terial, ultrafiltration membrane, advantageously ceramic material and ultrafiltration membrane that provide the capillary suction phenomenon.

The materials for the supporting base and for the filtration elements are selected based on process requirements by optimizing the properties. In an advan- tageous embodiment the supporting base is of composite material and the filtration elements are of ceramic material or ultrafiltration membrane.

The filtration elements are attached to the supporting base such that liquid removal channels are formed. The supporting base has several apart from each other located protrusions on both sides, which bond with the filtration element and form the channels for the liquid removal on both sides of the plate and provide support for the filtration elements. The protrusions are located in a pattern forming the channels; advantageously in mirror pattern in respect of the central axis running in radius direction of the sector design of the filter plate.

The supporting base is advantageously made by molding or by machining. The filtration elements are attached on both sides of the supporting base by adhesive by welding.

The filter plate is especially suitable for rotary vacuum disc filters, in which capillary suction filtration principle is applied.

By the invention and its advantageous features several benefits are achieved. The filter plate according to the invention provides for the optimization possibilities of material properties of the supporting base and the filtration element independently. The strength of the filter plate is increased in view of the ceramic filter plates; especially by using the advantageous materials i.e. stainless steel and carbon fiber reinforced composite material for the supporting base. The material selection of stainless steel of carbon fiber reinforced composite material for the supporting base also provides the possibility of increasing size of the filter disc and therefore the capacity of filters as the weight can be reduced by the advantageous material selection of the supporting base of the filter plate. Also the impact resistance strength is increased when comparing to ceramic filter plates.

In the following the invention is described with reference to the accompanying drawing in which In figures 1 A - 1 B are shown schematically an advantageous example of a filter plate according to the invention in a body structure view and an external view,

In figure 2 is shown schematically an example of the supporting base of the example presented in figures 1 A - 1 B,

In figure 3 is shown schematically top view of the example presented in figures 1 A - 1 B,

In figure 4 is shown schematically side view of the example presented in figures 1 A - 1 B, In figure 5 is shown schematically bottom view of the example presented in figures 1 A - 1 B

In figure 6 is shown schematically sectional view of the filtration element attached to the supporting bas and

In figures 7A - 7C are shown schematically a filter disc assembly of filter plates and fastening details thereof.

During the course of the following description of figures 1 A - 7C corresponding reference numbers and signs will be used to identify like elements, parts and part components unless otherwise mentioned. In the figures some references sign have not been repeated for clarity reasons. In the following the examples are described mainly by reference to a filter plate of a disc filter in view of simplifying the disclosure but it should be noted that instead of this example any type of a filter plate can have similar features and properties in accordance with the invention.

In figures 1 A - 1 B are shown schematically an advantageous example of a fil- ter plate 10 according to the invention in a body structure view, figure 1 A and in an external view, figure 2B. The filter plate 10 has a circle sector shape and is a planar structure. Around the filter plate 10 are upper edge 1 1 , side edges 12 and bottom edge 14 thus forming the edges of the supporting base 26 of the filter plate 10. The upper edge 1 1 and the bottom edge 12 are curved and the side edges 12 are straight. Above the lower edge 14 a bottom part 13 that also forms a part of the supporting base 26. At the lower edge 14 a tube con- nector 15 for liquid is located via which liquid is led to a collecting pipe (figures 7 A and 7C). In figure 1 B the filter plate 10 is shown as an external view having on both planar sides i.e. on front as shown in the figure 1 B and on back (on the behind as seen in the figure 1 B) a filtration element 16, which in figure 1 A is partly removed. The supporting base 26 has protrusions 21 that protrude from the supporting base 26 forming liquid removal channels 21 . The supporting base 26 has thus several apart from each other located protrusions 20 on each side of the supporting base 26, which support the filtration element 16 and form the channels 21 for the liquid removal on both sides of the filter plate 10 and provide support to the filtration elements 16. The protrusions 20 are located in a pattern forming the channels 21 ; advantageously in mirror pattern in respect of the central axis 24 (figure 2) running in radius direction of the sector design of the filter plate 10.

In figure 2 is shown schematically an example of the body structure of the ex- ample presented in figures 1 A - 1 B. The filter plate 10 has a circle sector shape and is a planar structure. Around the filter plate 10 are upper edge 1 1 , side edges 12 and bottom edge 14 thus forming the edges of the supporting base 26 of the filter plate 10. The upper edge 1 1 and the bottom edge 12 are curved and the side edges 12 are straight. Above the lower edge 14 a bottom part 13 that also forms a part of the supporting base 26. At the lower edge 14 a tube connector 15 for liquid is located via which liquid is led to a collecting pipe (figures 7A and 7C). The supporting base 26 has protrusions 21 that protrude from the supporting base 26 forming liquid removal channels 21 . The supporting base 26 has thus several apart from each other located protrusions 20 on each side of the supporting base 26 arranged in curved protrusion rows 25, which support the filtration element 16 and form the channels 21 for the liquid removal on both sides of the filter plate 10 and provide support to the filtration elements 16. The protrusions 20 are located in a pattern forming the channels 21 ; advantageously in mirror pattern in respect of the central axis 24 running in radius direction of the sector design of the filter plate 10.

In figure 3 is shown schematically top view of the example presented in figures 1 A - 1 B. Between the side edges 1 1 is located a groove 17 for locking bars 31 to be fastened at one end of a connecting rod 32 to hold one filter plate 10 to those located next to it, see figures 7A and 7B. In figure 4 is shown schematically side view of the example presented in figures 1 A - 1 B. The side edges 12 are located on both planar sides of the filter plate and at the lower part of the filter plate 10 (in the figure on the right) is the tube connector 15. In figure 5 is shown schematically bottom view of the example presented in figures 1 A - 1 B. On the bottom side of the bottom edge 14 of the filter plate 10 is the tube connector 15 and on each side a cut 19 is located for space to install the connecting rod 32 between filter plates next to each other.

In figure 6 is shown schematically top cut off view of the example presented in figures 1 A - 1 B. The protrusions 20 of the supporting base 26 of the filter plate 10 from the liquid removal channels 21 in between of themselves and support on each side located filtration elements 16.

In figures 7A - 7C are shown schematically a filter disc assembly of filter plates and fastening details thereof. The filter plates 10 are attached to each other to form a circular filter disc 30 attached to a shaft 35 by connecting rods 32(fig. 7B). On the outer circumference the filter plates 10 are fastened to each other by locking bar 31 (fig 7B) and at the other end to the shaft 35 at fastening points 33.

As can be seen from the figures 1 A - 7C the filter plate 10 is formed as a sandwich structure comprising two different types of main parts 16, 26, one of which is a supporting base 26 and the other is the filtration element 16. On each side of the supporting base 26 one filtration element 16 is attached. The supporting base 26 is made of metallic or composite material; advantageous materials are stainless steel and carbon fiber reinforced composite material, which both have good impact resistance properties. The material of the filtration element 16 is selected based on the requirements of the filtration process. It can be filtration cloth material, mesh material, ceramic material, ultrafiltration membrane; advantageously the filtration element 16 is made of ceramic material or ultrafiltration membrane that provide the capillary suction phenomenon. The materials for the supporting base 26 and for the filtration elements 16 are selected based on process requirements by optimizing the properties. In an advantageous embodiment the supporting base 26 is of composite material and the filtration elements 16 are of ceramic material or ultrafiltration membrane. Each filtration element 16 is attached to the supporting base 26 such that liquid removal channels 21 are formed. The supporting base 26 has several apart from each other located protrusions 20 on each side of the supporting base 26, which support the filtration element 16 and form the channels 21 for the liquid removal on both sides of the element 10 and provide further strength for the supporting base 26. The protrusions 20 are located in protrusion rows 25 in a pattern forming the channels 21 ; advantageously in mirror pattern in respect of the central axis 24 running in radius direction of the sector design of the filter plate 10. The filtration elements 16 are attached on both sides of the supporting base 26 by adhesive or by welding. Above only some advantageous examples of the invention have been described to which the invention is not to be narrowly limited. It is clear to one skilled in the art that many modifications and variations are possible with in the invention as defined in the following claims.

Reference signs used in the drawing:

10 filter plate

1 1 upper edge

12 side edge

13 bottom part

14 lower edge

15 tube connector

16 filtration element

17 groove

19 cut for a connecting rod

20 protrusion

21 liquid removal channels

24 imaginary central axis

25 protrusion row

26 supporting base

30 filter disc

31 locking bar

32 connecting rod

33 fastening point

35 shaft

Claims

1 . Filter plate (10) of a filter disc (30), which has a circle sector shape and a planar structure, characterized in that the filter plate (10) is formed as a sandwich structure comprising a supporting base (26) and a filtration element (16) on both planar sides of the filter plate (10).

2. Filter plate according to claim 1 , characterized in that the materials for the supporting base (26) and for the filtration elements (16) are selected based on process requirements by optimizing the properties.

3. Filter plate according to claim 1 or 2, characterized in that the supporting base (26) is made of metallic or composite material, advantageously of carbon fiber reinforced composite material.

4. Filter plate according to any of previous claims, characterized in that the material of the filtration element (16) is filtration cloth material, mesh material, ceramic material, ultrafiltration membrane, advantageously made of ceramic material or ultrafiltration membrane that provide capillary suction phenomenon.

5. Filter plate according to any of previous claims, characterized in that the filtration elements (16) are attached on both sides of the supporting base (26) by adhesive or by mechanical fastening or by welding.

6. Filter plate according to any of previous claims, characterized in that the filter plates (10) are fastened by connecting rods (32) that go through space between two neighboring filter plates (10), that one end of the connecting rod (32) is fastened at fastening points (33) on a shaft

(35) of the filter and that other end of the connecting rod (32) is fastened by a locking bar (31 ) which is fitted into a groove at top of the two neighboring filter plates (10).

7. Filter plate according to any of previous claims, characterized in that filter plates (10) are attached to each other to form a circular filter disc

(30) and attached to a shaft (35) of a disc filter by connecting rods (32) and that on the outer circumference the filter plates (10) are fastened to each other by locking bar (31 ).

Filter plate according to any of previous claims, characterized in that the supporting base (26) has protrusions (20) that protrude from the supporting base (26) forming liquid removal channels (21 ).

Filter plate according to any of previous claims, characterized in that the supporting base (26) has thus several apart from each other located protrusions (20) on each side of the supporting base (26) arranged in curved protrusion rows (25) in a pattern, advantageously in mirror pattern in respect of an imaginary central axis (24) running in radius direction of the sector design of the filter plate (10).